Mechanical Properties of Cellulose Fibers Reinforced Thermoplastics

Cellulose fibers are selected as a reinforced filler for thermoplastics due to their superior mechanical properties and lower price compared to the thermoplastics. In the present study chemithermomechanical pulp of hard wood (aspen) fibers having selected aspect ratio (length/diameter) were first encapsulated with polystyrene and then mixed with polystyrene polymer at various concentrations. Mechanical properties were measured on compression molded samples containing between 10 and 40 weight percent of cellulose fibers. Experimental results show a signifi cant increase in tensile stress and modulus with fiber concentration. Using the constituent properties, an efficiency factor of stress transfer between fiber and polymer matrix was calculated and was shown to be constant for the various fiber concentrations. Theoretical predictions of tensile stress and modulus using the basic composite theory have been made. Large differences between experimental results and theoretical predictions have been observed and will be discussed in terms of fiber orientation and fiber aspect ratio.